Paul Crabaugh wrote an article on customizing character classes for Basic/Expert D&D which was published back in Dragon #109. It actually worked fairly well, although it was best if all characters used to customized class system if any did due to the high number of experience points classes created via the customized system required.

I've discovered a web page that generates a random customized character class using Paul Crabaugh's system every time the page reloads. I'm not really sure how useful this is as randomized seems the opposite of customized, but it is really neat to use.